Here's an excellent quote on sitting meditation (zazen) I found at today's Daily Dharma page at Tricycle.com.

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Ajahn Chah, in Samuel Bercholz's Entering the Stream

Let the mind unite in a single point and let that composed mind dwell with the breath. Let the breath be its sole object of knowledge. Concentrate until the mind becomes increasingly subtle, until feelings are insignificant and there is a great inner clarity and wakefulness. Then when painful sensations arise they will gradually cease of their own accord. Finally you'll look on the breath as if it was a relative come to visit you. When a relative leaves, we follow him out and see him off. We watch until he's walked or driven out of sight, and then we go back indoors. We watch the breath in the same way. If the breath is coarse, we know that it's coarse; if it's subtle, we know that it's subtle. As it becomes increasingly fine, we keep following it, while simultaneously awakening the mind. Eventually the breath disappears altogether and all that remains is the feeling of wakefulness. This is called meeting the Buddha.